Project Summary My long-term goal is to identify how individuals can mitigate exposures to the deleterious health effects of air pollution through practical lifestyle adjustments. My primary project objective is to investigate how an individual's choices influence personal exposures to traffic-related air pollutants (TRAP) and the corresponding acute health effects. It has been reported that traffic pollutants may cause up to half of all air pollution related mortalities. Despite the burden from such widespread, involuntary exposures, few studies have examined the magnitude of personal exposures due to commuting exposures. A commuter's exposure is dependent on the mode of transport, time of day, route, and fuel type. Public transportation, bicycling, and walking have been promoted as ways to reduce air pollution by reducing the vehicle fleet, yet few studies have examined how exposures would be modified due to a change in the mode of transportation or the subsequent health effects. In this study, 65 participants will be asked to utilize two modes of transportation (car and either bicycle, rail, or bus) during their typical commute over 4 days (two days per mode). During each 24-hr period, the participants will be examined for changes in oxidative stress biomarkers and acute cardiovascular and respiratory endpoints and 7+ pollutants and noise levels will be quantified in real-time. I hypothesize that there will be a significant association between exposure levels and acute health endpoints. An examination will be conducted into whether this association is modified by mode of transport. I will also examine the influence of the time of day an individual chooses to commute to work and exercise outdoors in a second cohort of 75 participants. Since TRAP tends to be most concentrated during two relatively short periods of time (morning and evening rush hours), I hypothesize that altering the time of exposure will notably change personal exposures. This project will bring in a key components of the personal exposure paradigm, an individual's decision- induced reductions in exposure. We will identify modifiable factors/personal choices that can reduce exposures with the objective of identifying which reductions in exposure can lead to meaningful health benefits. This knowledge will enable individuals to make lifestyle choices that can reduce their exposure independent of the ambient air quality or regulatory changes. This will be particularly beneficial in the study location (Baltimore), where the combustion-related mortality rate is highest in the U.S. It is expected that the information obtained in this K99/R00 will be applicable to other metropolitan areas with similar infrastructure. Through this research, my didactic coursework, and the guidance of my mentoring team (comprised of a pulmonologist, a biostatistician, an environmental epidemiologist, and an exposure scientist), I will acquire critical skills required to be a successful, independent researcher in environmental health sciences.